Codex-Ct-2 Experiment: Long Term Treatment in High Temperature Hydrogen and Water Quenching of a Fuel Bundle

The simulation of the Paks-2 incident was carried out in the frame of an experimental programme in the CODEX facility with electrically heated fuel rod bundles. The main boundary conditions for the CODEX-CT-2 were similar to the previous CODEX-CT-1 test. The most significant difference between the two tests was the operation of the air let down valve that was open in the first test and closed in the second one. In the second test the hydrogen produced in the Zr-steam reaction could not escape from the test section and it prevented the access of steam to the Zr surfaces and caused much less oxidation than was observed in the first tests. The final quench by water led to temperature excursion in the bundle and in the shroud. The final state of the bundle was very brittle, the fuel rods and the shroud were cracked and fragmented.